This disclosure describes methods that enable the selective functionalization and assembly of the silicon-oxygen frameworks in polyhedral oligomeric silsesquioxane (POSS) cage molecules. It is desired to selectively manipulate the frameworks of POSS compounds because they are useful as chemical species that can be further converted or incorporated into a wide variety of chemical feed-stocks useful for the preparation of catalyst supports (Weidner et al., “Organooligosilsesquioxanes” U.S. Pat. No. 5,047,492; U.S. patent application Ser. No. 60/147,435; Vogt, L. H., Brown, J. F., Inorg. Chem., 1963, 2, 189-92), monomers, polymers, and as solubilized forms of silica that can be used to replace fumed and precipitated silicas or in biological applications, and for surface modification. When incorporated into a polymeric material POSS can impart new and improved thermal, mechanical and physical properties to common polymeric materials. (See Schmid, G.; Pugin, R.; Malm, J-O.; Bovin, J-O. “Silsesquioxanes as Ligands for Gold Clusters,” Eur. J. Inorg. Chem. 1998, pp813-817. Developed a process for the cornercapping of trisilanols with silane reagents MeO)3Si(CH2)3SH using p-toluenesulfonic acid. This is a process that was necessary to enable corner capping with this functionality. Note that Marsmann et al. have reported the synthesis of a similar thiol-functionalized POSS by co-hydrolysis of trtichloro(n-propyl)silane with the (3-mercaptopropyl)trimethoxysilane in a 7:1 ratio. See B. J. Hendan, H. C. Marsmann, J. Organomet. Chem. 1994, 483, pp33 and U.Dittmar, B. J. Hendan, U. Floerke, H. C. Marsmann, J. Organomet. Chem. 1995, 485, p185.)
Prior art has shown that a variety of POSS-silanol frameworks can be functionalized via silation using a variety of silyl and metal-based agents. ((a) Feher et al., “Silsesquioxanes as Models for Silica Surfaces”, J. Am. Chem. Soc. 1989, 111, 1741-48. (b) Weidner et al., “Organooligosilsesquioxanes” U.S. Pat. No. 5,047,492. (c) Brown, J. F., Vogt, L. H., “The Polycondensation of Cyclohexylsilanetriol” J. Am. Chem. Soc. 1965, 87, 4313-24.) While synthetically useful, this prior functionalization method is imperfect in that it requires the use of dry solvents and the presence of proton accepting bases (e.g. amines) to produce the desired product in high yield. In addition the prior method is cumbersome and costly in that additional precautions must be taken when handling chlorosilanes and related metal halides. Furthermore the prior art was effective only for certain functionalities and in particular did not allow the use of amino, epoxy, and hydrido functionalized silane coupling agents. Later art reported a limited usage of alkoxy silane coupling agents in reaction with POSS-Silanols in the presence of acid to produce the desired fully condensed functionalized POSS systems [(RSiO1.5)n(YSiO1.5)1]Σ#. (See Schmid, G.; Pugin, R.; Maim, J-O.; Bovin, J-O. “Silsesquioxanes as Ligands for Gold Clusters,” Eur. J. Inorg. Chem. 1998, pp813-817; See B. J. Hendan, H. C. Marsmann, J. Organomet. Chem. 1994, 483, pp33 and U.Dittmar, B. J. Hendan, U. Floerke, H. C. Marsmann, J. Organomet. Chem. 1995, 485, p185.) This advancement was however found to be of modest utility in that it does not afford the desired [(RSiO1.5)n(YSiO1.5)1]Σ# products in high yield and free from resinous byproduct contaminates.
Therefore an improvement of the prior art was necessary to enable the economical and commercial-scale functionalization of POSS-silanols from low-cost and safe (non halogenated) coupling agents bearing the a widest possible range of functionalities and leaving groups. In the course of development of an improved functionalization method, a discovery was made that enabled the efficient (one-step) assembly of polyfunctional POSS systems from these same coupling agents. The latter discovery directly resulted in many new and previously only theorized POSS compositions.
It should also be noted that indirectly related prior art has reported that bases such as NaOH, KOH, etc. can be used to both catalyze the polymerization of fully condensed POSS [(RSiO1.5)n]Σ# into lightly networked polysilsequioxane resins [RSiO1.5]∞ or to convert selected polysilsesquioxane resins [RSiO1.5]∞ into fully condensed POSS structures [(RSiO1.5)n]Σ#. ((a) Hybrid Plastics U.S. Pat. Pending Ser. No. 60/147,435. (b) Vogt, L. H., Brown, J. F., Inorg. Chem., 1963, 2, 189-92) This prior art does not afford the selective assembly of POSS nanostructures from highly functionalized silane coupling agents (e.g. YSiX3) nor does it afford the functionalization of POSS Silanols with functionalized silane coupling agents. Furthermore the prior art does not provide methods of producing POSS systems suitable for functionalization and subsequent polymerization or grafting reactions. This oversight in the prior art is reflective of the fact that the invention of POSS-based reagents, monomers and polymer technology post-dates this prior art by approximately three decades. Hence POSS compositions and processes relevant to the types of systems desired for POSS monomer/polymer technology were not envisioned in the prior art. Additionally the prior art does not demonstrate the action of bases on silane, silicate, or silsesquioxane feedstocks suitable for producing low-cost and high purity POSS systems. In contrast to the prior art (Brown et al., and Marsmann et al.) the processes taught here and the compositions claimed specifically enable the development of lower cost, high purity POSS systems bearing functionalities useful as derivitizable chemical reagents and feedstocks.